Generally, conventional automotive lighting systems utilize filament bulbs as a lighting source. However, filament bulbs have many drawbacks, including high consumption of electrical power, the generation of great amounts of heat, and readily breakable filaments. Recently, due to these drawbacks, light emitting semiconductor devices (LESDs), such as light emitting diodes (“LEDs”), have been adapted for use in certain automobile lighting systems.
LEDs solve many of the problems associated with filament bulbs, because they emit light using a lower voltage and current than used by a filament bulb and are less prone to breakage. However, various other problems are associated with LEDs when used in automobile lighting systems. For example, typical LEDs produce significantly less light than filament bulbs. Accordingly, a number of LEDs must be used within a particular light assembly to generate the requisite amount of light. As the number of LEDs is increased, the amount of heat generated by the LEDs increases. Alternatively, LEDs which operate at a significantly higher power may be used. Of course, as the power of the LED increases, the amount of heat generated also increases.
The increase in heat is a significant problem for LED systems. While the expected lifetime of an LED at room temperature may be tens of thousands of hours, that same LED when exposed to high temperatures may only last several thousand hours. Moreover, the amount of light emitted by an automotive lighting systems is a significant safety issue subject to various laws and regulations. Accordingly, an automotive lighting system must produce a stable luminous flux at all times throughout the lifetime of the lighting system. However, subjecting an LED to an increased temperature results in an immediate dimming of the LED at the time of exposure. Moreover, as an LED is exposed to increased temperatures over a period of time, the maximum achievable output of the LED is diminished even during uses at lower temperatures.
Therefore, a need exists for an automotive lighting system that efficiently provides for dissipation or removal of excess heat generated by LEDs within the lighting system.